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Review of sentinel lymph node credentialing: how many cases are enough?1
COLLECTIVE REVIEWS
Review of Sentinel Lymph Node Credentialing: How Many Cases Are Enough? Rache M Simmons, MD, FACS for sentinel node biopsy alone to a traditional axillary dissection. The false-negative rate is defined as how many patients with a negative sentinel node will actually have undetected axillary nodal metastases. The potential risk to these patients would be understaging and an increased risk of axillary recurrence. The impact on survival with an undissected positive axilla is currently debated. This important issue was addressed by the American Society of Breast Surgeons, which established a task force to suggest acceptable standards in SLNB. These recommendations are that the identification rate for SLNB be 85% or higher, and that a false-negative rate be 5% or less.5 The data on individual, institutional, and multiinstitutional learning curves are reviewed in this article to assess the number of SLNBs necessary to achieve these guidelines. Cox and associates6 published the learning curves for SLNB of the individual surgeons and composite summary curves from The Moffitt Cancer Center. These individual curves show that the number of cases needed to reach the 85% identification rate is quite variable. The combined institutional learning curves show that to consistently identify 85% of sentinel lymph nodes (a failure rate of less than 15%), 15 cases of SLNB are needed (Fig. 1). The combined individual learning curves of the surgeons at Northwestern University Medical School also show a great deal of variability in establishing proficiency at the technique. A summary of individual learning curves demonstrates that the sentinel node was identified in more than 85% of cases after 20 cases of SLNB7 (Fig. 2). The percentage of successful SLNBs was also shown by Cody and colleagues8 to be dependent on the number of cases performed. These data show the identification rate to be 86% for surgeons who performed 16 cases or less and 94% for surgeons who performed more than 84 SLNBs (p ⫽ 0.012). The overall false-negative rate was 10.6% in the first 500 SLNBs performed at this institution. If the first 6 cases per surgeon were excluded, this
Multiple studies have shown sentinel lymph node biopsy (SLNB) to be an accurate method of assessing the status of the axillary lymph nodes in patients with breast cancer.1-4 There are several advantages of SLNB over the traditional axillary dissection including a less invasive surgical procedure, elimination of postoperative drainage of the axilla, less patient discomfort, and decreased incidence in lymphedema or neurovascular injury. The SLNB can often be performed in an outpatient setting without the use of general anesthesia. This technique is rapidly becoming the new standard of care in the treatment of women with breast cancer and is replacing axillary dissection in many patients. This review summarizes the current recommendations in sentinel lymph node credentialing for surgeons. CREDENTIALING IN SENTINEL LYMPH NODE BIOPSY As SLNB replaces full axillary dissection as a new standard of care in breast cancer patients, its accuracy depends on the proficiency of the individual surgeon performing the procedure. The key question is, ”How many SLNBs with full axillary dissection must a surgeon perform to become adequately capable to perform the procedure alone?” The answer to this question is based on an acceptable identification rate and an acceptable falsenegative rate of SLNB. The identification rate is defined as the percentage of patients in whom a definitive sentinel lymph node is found. The potential risk of a low identification rate is that it obligates patients who are potential candidates No competing interests declared.
Received February 7, 2001; Revised March 30, 2001; Accepted April 2, 2001. This review was presented at the American College of Surgeons 86th Annual Clinical Congress, Chicago, IL, October 2000. Grant support from the Alice Russell Breast Cancer Research Fund and Rhea Finnell Breast Cancer Research Fund, Fashion Footwear of New York Breast Cancer Fund. From the Department of Surgery, New York-Presbyterian Hospital, Weill Medical College of Cornell University, and Strang-Cornell Breast Center, New York, NY. Correspondence address: Rache M Simmons, MD, FACS, 425 East 61st St, New York, NY 10021.
© 2001 by the American College of Surgeons Published by Elsevier Science Inc.
206
ISSN 1072-7515/01/$21.00 PII S1072-7515(01)00998-X
Simmons
Vol. 193, No. 2, August 2001
Sentinel Lymph Node Credentialing
207
Figure 1. Institutional learning curve from The Moffitt Cancer Center.
rate dropped to 5.2%, and if the first 15 cases per surgeon were excluded, the rate fell to 2%. Tafra and coworkers9 established a multiinstitutional SLNB registry including 648 breast cancer patients with 48 surgeons. These surgeons represented 18 academic and community practices. The learning curves from this registry show that the identification rate for those surgeons performing 10 or fewer SLNBs to be 81%, and those performing more than 10 cases to be 91% (p ⫽ 0.005) (Table 1). Likewise, the false-negative rates for surgeons performing 10 or fewer SLNBs was 15% and
for those performing more than 10 SLNBs it was 4% (Table 2). The largest multiinstitutional SLNB series by McMasters10 included 1,564 patients and 165 surgeons. The majority of these surgeons had community general surgery practices. On entering the registry only 7 surgeons had performed more than 10 SLNBs so the data truly represent the learning curves for most of participants. The data obtained showed that, on average, an acceptable identification rate was established fairly quickly within the first 10 cases (Table 3). The
Figure 2. Institutional learning curve from Northwestern University Medical School.7
208
Simmons
Table 1. Multiinstitutional Learning Curves: ECU Medical Center SLNB Registry: Identification Rate
Surgical experience
Cases (n)
Identification rate (%)
ⱕ10 ⬎10
81 91
p ⫽ 0.005. SLNB, sentinel lymph node biopsy.
Table 3. Multiinstitutional Learning Curves: University of Louisville SLNB Registry University of Louisville SLNB Registry Surgeons (n)
0–10 11–20 21–30 ⬎30
165 35 16 7
Total patients SLN SLN identification (n) identified rate (%)
812 350 160 132
Table 2. Multiinstitutional Learning Curves: ECU Medical Center SLNB Registry: False-Negative Rate
Surgical experience
Cases (n)
Falsenegative rate (%)
ⱕ10 ⬎10
15 4
p ⫽ 0.18. SLNB, sentinel lymph node biopsy.
false-negative rate dropped significantly after the first 20 cases from 9.6% to 1.3% (p ⫽ 0.01) (Table 4). Controversy exists in regard to the best technique of performing sentinel node biopsy (blue dye or isotope alone or in combination), the method of injection of isotope (intraparenchymal or intradermal), and the location of injection (peritumoral or periareolar). McMasters10 did show that the accuracy of sentinel node biopsy was increased by using blue dye and isotope technique simultaneously. In light of the presented data, we, as surgeons, must admit that a learning curve exists in the technique of SLNB and that surgeons master the procedure at different rates. A summary of the current data of SLNB learning curves (Table 5) shows the identification rate of 85% and a false-negative rate of 5% are achieved on average in 10 to 20 cases. It is the recommendation of the American Society of Breast Surgeons, as of September 1, 2000, to suggest 20 cases of SLNB with backup axillary dissections for surgeons learning the techniques of SLNB.5 It is critical that each individual surgeon establish his or her own identification rate and false-negative rate and only start performing SLNB alone when the appropriate proficiency has been achieved. It is also recommended that after abandoning backup axillary dissections, surgeons should report axillary recurrences, ideally to a national registry. These local recurrences should remain less than
SLNBs performed (n)
J Am Coll Surg
Sentinel Lymph Node Credentialing
702/812 328/350 158/160 123/132
SLN, sentinal lymph node; SLNB, sentinel lymph node biopsy.
86 94 99 93
5%. There are two current national sentinel node clinical trials into which patients can be registered. These include the American College of Surgeons Oncology Group Z-10/Z-11 Trial and the National Surgical Bowel and Breast Project B-32 Trial. These trials offer an excellent opportunity to evaluate outcomes of the sentinel node biopsy technique. There is currently no national credentialing for SLNB. This review is a summary of the available data on individual, institutional, and multiinstitutional learning curves and the recommendation of the American Society of Breast Surgeons. The credentialing and privileging of SLNB remains a policy of the individual hospital or institution. Unanswered issues in credentialing include whether this number should be less for surgeons who receive formal training in accredited continuing medical education courses in SLNB technique, for surgeons proctored by a surgeon experienced in SLNB technique, and for those trained in SLNB technique as residents or fellows. It is most productive to have not just the surgeon, but also the treatment team including the nuclear medicine physicians and pathologists trained in sentinel node biopsy technique, to optimize its incorporation into routine practice. Surgeons can also find it beneficial to disTable 4. Multiinstitutional Learning Curves: University of Louisville SLNB Registry SLNBs performed (n)
Surgeons (n)
Total cases (n)
FN/TPⴙFN
FN rate (%)
0–10 11–20 21–30 ⬎30 0–20 ⬎20
165 35 16 7 165 16
812 350 160 132 1162 292
23/256 10/87 0/35 1/44 33/343 1/79
9.0 11.5 0 2.3 9.6 1.3ⴱ
p ⫽ 0.01. FN, false negative. (From: K McMasters, University of Louisville, data presented at the American Society of Breast Surgeons meeting, April 1999, with permission.)
Simmons
Vol. 193, No. 2, August 2001
Table 5. Sentinel Lymph Node Biopsy Learning Curves: Summary Institution
Moffitt Northwestern Memorial Sloan Kettering Cancer Center ECU Multicenter Louisville Multicenter
Identification rate 85% (n)
False-negative rate 5% (n)
15 20
Not determined Not determined
16 10 10
15 10 20
cuss potential treatment and staging issues of sentinel node biopsy alone with their institutional colleagues in medical oncology and radiation oncology before abandoning axillary dissection in sentinel node-negative patients. Acknowledgment: American Society of Breast Surgeons Sentinel Lymph Node Task Force members: Michael Edwards, MD; Armando Giuliano, MD; Douglas Reintgen, MD; Lorraine Tafla, MD; and Patrick Whitworth, MD.
REFERENCES 1. Giuliano AE, Kirgan DM, Guenther JM, Morton DL. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg 1994;220:391–401.
Sentinel Lymph Node Credentialing
209
2. Giuliano AE, Haigh PI, Brennan M, et al. Prospective observational study of sentinel lymphadenectomy without further axillary dissection in patients with sentinel node negative breast cancer. J Clin Oncol 2000;18:2553–2559. 3. O’Hea BJ, Hill AD, El-Shirbiny AM, et al. Sentinel lymph node biopsy in breast cancer: Initial experience at Memorial Sloan-Kettering Cancer Center. J Am Coll Surg 1998;186:423–427. 4. Albertini JJ, Lyman GH, Cox CE, et al. Lymphatic mapping and sentinel node biopsy in the patient with breast cancer. JAMA 1996;276:1818–1822. 5. The American Society of Breast Surgeons. Consensus statement on guidelines for performance of sentinel lymphadenectomy for breast cancer. September 1, 2000. 6. Cox CE, Bass SS, Boulware D, et al. Implementation of new surgical technology: outcome measures for lymphatic mapping of breast carcinomas. Ann Surg Oncol 1999;6:553–561. 7. Morrow M, Rademaker AW, Bethke KP, et al. Learning sentinel node biopsy: Results of a prospective randomized trial of two techniques. Surgery 1999;126:714–722. 8. Cody H, Hill A, Tran KN, et al. Credentialing for breast lymphatic mapping: how many cases are enough? Ann Surg 1999;229:723–728. 9. Tafra L, Swanson M, Van Eyk J, et al. Multi-center trial of sentinel node biopsy for breast cancer using both technetium sufur colloid and isosulfan blue dye. Ann Surg 2001;233:51–59. 10. McMasters KM. Credentialing issues: The University of Louisville Breast Cancer Sentinel Lymph Node Study. Forthcoming.
Review of Sentinel Lymph Node Credentialing: How Many Cases Are Enough? Rache M Simmons, MD, FACS for sentinel node biopsy alone to a traditional axillary dissection. The false-negative rate is defined as how many patients with a negative sentinel node will actually have undetected axillary nodal metastases. The potential risk to these patients would be understaging and an increased risk of axillary recurrence. The impact on survival with an undissected positive axilla is currently debated. This important issue was addressed by the American Society of Breast Surgeons, which established a task force to suggest acceptable standards in SLNB. These recommendations are that the identification rate for SLNB be 85% or higher, and that a false-negative rate be 5% or less.5 The data on individual, institutional, and multiinstitutional learning curves are reviewed in this article to assess the number of SLNBs necessary to achieve these guidelines. Cox and associates6 published the learning curves for SLNB of the individual surgeons and composite summary curves from The Moffitt Cancer Center. These individual curves show that the number of cases needed to reach the 85% identification rate is quite variable. The combined institutional learning curves show that to consistently identify 85% of sentinel lymph nodes (a failure rate of less than 15%), 15 cases of SLNB are needed (Fig. 1). The combined individual learning curves of the surgeons at Northwestern University Medical School also show a great deal of variability in establishing proficiency at the technique. A summary of individual learning curves demonstrates that the sentinel node was identified in more than 85% of cases after 20 cases of SLNB7 (Fig. 2). The percentage of successful SLNBs was also shown by Cody and colleagues8 to be dependent on the number of cases performed. These data show the identification rate to be 86% for surgeons who performed 16 cases or less and 94% for surgeons who performed more than 84 SLNBs (p ⫽ 0.012). The overall false-negative rate was 10.6% in the first 500 SLNBs performed at this institution. If the first 6 cases per surgeon were excluded, this
Multiple studies have shown sentinel lymph node biopsy (SLNB) to be an accurate method of assessing the status of the axillary lymph nodes in patients with breast cancer.1-4 There are several advantages of SLNB over the traditional axillary dissection including a less invasive surgical procedure, elimination of postoperative drainage of the axilla, less patient discomfort, and decreased incidence in lymphedema or neurovascular injury. The SLNB can often be performed in an outpatient setting without the use of general anesthesia. This technique is rapidly becoming the new standard of care in the treatment of women with breast cancer and is replacing axillary dissection in many patients. This review summarizes the current recommendations in sentinel lymph node credentialing for surgeons. CREDENTIALING IN SENTINEL LYMPH NODE BIOPSY As SLNB replaces full axillary dissection as a new standard of care in breast cancer patients, its accuracy depends on the proficiency of the individual surgeon performing the procedure. The key question is, ”How many SLNBs with full axillary dissection must a surgeon perform to become adequately capable to perform the procedure alone?” The answer to this question is based on an acceptable identification rate and an acceptable falsenegative rate of SLNB. The identification rate is defined as the percentage of patients in whom a definitive sentinel lymph node is found. The potential risk of a low identification rate is that it obligates patients who are potential candidates No competing interests declared.
Received February 7, 2001; Revised March 30, 2001; Accepted April 2, 2001. This review was presented at the American College of Surgeons 86th Annual Clinical Congress, Chicago, IL, October 2000. Grant support from the Alice Russell Breast Cancer Research Fund and Rhea Finnell Breast Cancer Research Fund, Fashion Footwear of New York Breast Cancer Fund. From the Department of Surgery, New York-Presbyterian Hospital, Weill Medical College of Cornell University, and Strang-Cornell Breast Center, New York, NY. Correspondence address: Rache M Simmons, MD, FACS, 425 East 61st St, New York, NY 10021.
© 2001 by the American College of Surgeons Published by Elsevier Science Inc.
206
ISSN 1072-7515/01/$21.00 PII S1072-7515(01)00998-X
Simmons
Vol. 193, No. 2, August 2001
Sentinel Lymph Node Credentialing
207
Figure 1. Institutional learning curve from The Moffitt Cancer Center.
rate dropped to 5.2%, and if the first 15 cases per surgeon were excluded, the rate fell to 2%. Tafra and coworkers9 established a multiinstitutional SLNB registry including 648 breast cancer patients with 48 surgeons. These surgeons represented 18 academic and community practices. The learning curves from this registry show that the identification rate for those surgeons performing 10 or fewer SLNBs to be 81%, and those performing more than 10 cases to be 91% (p ⫽ 0.005) (Table 1). Likewise, the false-negative rates for surgeons performing 10 or fewer SLNBs was 15% and
for those performing more than 10 SLNBs it was 4% (Table 2). The largest multiinstitutional SLNB series by McMasters10 included 1,564 patients and 165 surgeons. The majority of these surgeons had community general surgery practices. On entering the registry only 7 surgeons had performed more than 10 SLNBs so the data truly represent the learning curves for most of participants. The data obtained showed that, on average, an acceptable identification rate was established fairly quickly within the first 10 cases (Table 3). The
Figure 2. Institutional learning curve from Northwestern University Medical School.7
208
Simmons
Table 1. Multiinstitutional Learning Curves: ECU Medical Center SLNB Registry: Identification Rate
Surgical experience
Cases (n)
Identification rate (%)
ⱕ10 ⬎10
81 91
p ⫽ 0.005. SLNB, sentinel lymph node biopsy.
Table 3. Multiinstitutional Learning Curves: University of Louisville SLNB Registry University of Louisville SLNB Registry Surgeons (n)
0–10 11–20 21–30 ⬎30
165 35 16 7
Total patients SLN SLN identification (n) identified rate (%)
812 350 160 132
Table 2. Multiinstitutional Learning Curves: ECU Medical Center SLNB Registry: False-Negative Rate
Surgical experience
Cases (n)
Falsenegative rate (%)
ⱕ10 ⬎10
15 4
p ⫽ 0.18. SLNB, sentinel lymph node biopsy.
false-negative rate dropped significantly after the first 20 cases from 9.6% to 1.3% (p ⫽ 0.01) (Table 4). Controversy exists in regard to the best technique of performing sentinel node biopsy (blue dye or isotope alone or in combination), the method of injection of isotope (intraparenchymal or intradermal), and the location of injection (peritumoral or periareolar). McMasters10 did show that the accuracy of sentinel node biopsy was increased by using blue dye and isotope technique simultaneously. In light of the presented data, we, as surgeons, must admit that a learning curve exists in the technique of SLNB and that surgeons master the procedure at different rates. A summary of the current data of SLNB learning curves (Table 5) shows the identification rate of 85% and a false-negative rate of 5% are achieved on average in 10 to 20 cases. It is the recommendation of the American Society of Breast Surgeons, as of September 1, 2000, to suggest 20 cases of SLNB with backup axillary dissections for surgeons learning the techniques of SLNB.5 It is critical that each individual surgeon establish his or her own identification rate and false-negative rate and only start performing SLNB alone when the appropriate proficiency has been achieved. It is also recommended that after abandoning backup axillary dissections, surgeons should report axillary recurrences, ideally to a national registry. These local recurrences should remain less than
SLNBs performed (n)
J Am Coll Surg
Sentinel Lymph Node Credentialing
702/812 328/350 158/160 123/132
SLN, sentinal lymph node; SLNB, sentinel lymph node biopsy.
86 94 99 93
5%. There are two current national sentinel node clinical trials into which patients can be registered. These include the American College of Surgeons Oncology Group Z-10/Z-11 Trial and the National Surgical Bowel and Breast Project B-32 Trial. These trials offer an excellent opportunity to evaluate outcomes of the sentinel node biopsy technique. There is currently no national credentialing for SLNB. This review is a summary of the available data on individual, institutional, and multiinstitutional learning curves and the recommendation of the American Society of Breast Surgeons. The credentialing and privileging of SLNB remains a policy of the individual hospital or institution. Unanswered issues in credentialing include whether this number should be less for surgeons who receive formal training in accredited continuing medical education courses in SLNB technique, for surgeons proctored by a surgeon experienced in SLNB technique, and for those trained in SLNB technique as residents or fellows. It is most productive to have not just the surgeon, but also the treatment team including the nuclear medicine physicians and pathologists trained in sentinel node biopsy technique, to optimize its incorporation into routine practice. Surgeons can also find it beneficial to disTable 4. Multiinstitutional Learning Curves: University of Louisville SLNB Registry SLNBs performed (n)
Surgeons (n)
Total cases (n)
FN/TPⴙFN
FN rate (%)
0–10 11–20 21–30 ⬎30 0–20 ⬎20
165 35 16 7 165 16
812 350 160 132 1162 292
23/256 10/87 0/35 1/44 33/343 1/79
9.0 11.5 0 2.3 9.6 1.3ⴱ
p ⫽ 0.01. FN, false negative. (From: K McMasters, University of Louisville, data presented at the American Society of Breast Surgeons meeting, April 1999, with permission.)
Simmons
Vol. 193, No. 2, August 2001
Table 5. Sentinel Lymph Node Biopsy Learning Curves: Summary Institution
Moffitt Northwestern Memorial Sloan Kettering Cancer Center ECU Multicenter Louisville Multicenter
Identification rate 85% (n)
False-negative rate 5% (n)
15 20
Not determined Not determined
16 10 10
15 10 20
cuss potential treatment and staging issues of sentinel node biopsy alone with their institutional colleagues in medical oncology and radiation oncology before abandoning axillary dissection in sentinel node-negative patients. Acknowledgment: American Society of Breast Surgeons Sentinel Lymph Node Task Force members: Michael Edwards, MD; Armando Giuliano, MD; Douglas Reintgen, MD; Lorraine Tafla, MD; and Patrick Whitworth, MD.
REFERENCES 1. Giuliano AE, Kirgan DM, Guenther JM, Morton DL. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg 1994;220:391–401.
Sentinel Lymph Node Credentialing
209
2. Giuliano AE, Haigh PI, Brennan M, et al. Prospective observational study of sentinel lymphadenectomy without further axillary dissection in patients with sentinel node negative breast cancer. J Clin Oncol 2000;18:2553–2559. 3. O’Hea BJ, Hill AD, El-Shirbiny AM, et al. Sentinel lymph node biopsy in breast cancer: Initial experience at Memorial Sloan-Kettering Cancer Center. J Am Coll Surg 1998;186:423–427. 4. Albertini JJ, Lyman GH, Cox CE, et al. Lymphatic mapping and sentinel node biopsy in the patient with breast cancer. JAMA 1996;276:1818–1822. 5. The American Society of Breast Surgeons. Consensus statement on guidelines for performance of sentinel lymphadenectomy for breast cancer. September 1, 2000. 6. Cox CE, Bass SS, Boulware D, et al. Implementation of new surgical technology: outcome measures for lymphatic mapping of breast carcinomas. Ann Surg Oncol 1999;6:553–561. 7. Morrow M, Rademaker AW, Bethke KP, et al. Learning sentinel node biopsy: Results of a prospective randomized trial of two techniques. Surgery 1999;126:714–722. 8. Cody H, Hill A, Tran KN, et al. Credentialing for breast lymphatic mapping: how many cases are enough? Ann Surg 1999;229:723–728. 9. Tafra L, Swanson M, Van Eyk J, et al. Multi-center trial of sentinel node biopsy for breast cancer using both technetium sufur colloid and isosulfan blue dye. Ann Surg 2001;233:51–59. 10. McMasters KM. Credentialing issues: The University of Louisville Breast Cancer Sentinel Lymph Node Study. Forthcoming.